This invention relates to control circuitry for a radio telephone, and more particularly, to stored program control for a radio telephone.
2. Description of the Prior Art
In the prior art, radio telephone control circuitry has been mechanized with discrete logic elements, resulting in a large number of circuit elements which physically occupy a large amount of space. This size restriction has dictated that the control circuitry must be located in the cradle, not in the handset. A large number of logic elements complicates the control circuitry. The highly complex control circuitry is relatively expensive to build and maintain.
The control circuitry of the prior art is inflexible and not easily changed or enhanced. In order to accommodate optional features additional control circuitry must be added.
Prior radio telephones have primarily used the rotary dial to produce the dialed digits. The rotary dial introduces dial pulse distortion due to the inherent inaccuracy of the dialing mechanism. This problem has been partially overcome by utilizing dual tone dialing circuits.
The radio channel selection has previously been accomplished by individual manually operated switches or by multiposition rotary switches. Expanded automatic and selective channel selection is presently not available.
The foregoing deficiencies reveal a long felt need for a stored program control circuitry for radio telephones that overcomes these limitations.